1. Field of Invention
This invention relates to elastomeric compression springs. The preferred embodiment of our invention is primarily directed to a novel compression spring formed of a minimum quantity of an elastomer that is oriented in the radial direction to provide a low spring rate. The invention has broad, varied applications that may include use as an auxiliary spring for eliminating side loads in the struts of automobiles, replacement of the spring damper system of small automobiles, vibration isolation for engine and for vehicle platforms, and energy absorption in athletic shoes.
2. Related Art.
Some light weight automobiles such as the Cutless Supreme.RTM. and Lumina.RTM. of General Motors Corporation have required auxiliary springs to balance the moments about and to eliminate side loads imposed upon their strut assemblies. An auxiliary spring developed and successfully sold for that purpose is depicted in FIG. 2 of the drawings. It is formed of a copolyester polymer elastomer manufactured and sold under the designation 4069 by E. I. duPont de Nemoirs under the trademark Hytrel.RTM.. This related art is more fully described in the "Detail Description" of this application. Additional prior art related to the present invention are U.S. Pat. Nos. 4,198,037 and 4,566,678 which issued to Miner Enterprises, Inc. on applications of David G. Anderson. Each of these patents focus on a method of manufacture of compression springs from the Hytrel.RTM. material and its associated compression set problems. Both are primarily directed to applications requiring very high spring rates for absorbing substantial quantities of energy in applications such as the railcar industry. In addition, they focus on elimination of the compression set problem through an axial, rather than a radial, precompression step during manufacture.